This application seeks partial support for the Federation of American Societies of Experimental Biology (FASEB) conference on Genetic Recombination and Genome Rearrangements to be held August 2-7, 2009 in Snowmass, Colorado. The 2009 Conference on Genetic Recombination and Chromosome Rearrangements will be the thirteenth in a series of highly successful bi-annual conferences devoted to these topics. This conference aims to join investigators studying many diverse aspects of genetic recombination, in a range of biological systems and with different experimental approaches. Presentations will introduce new and unpublished work on timely questions in the field and will include discussion from all participants. The FASEB conference provides unique opportunities for the exchange of information and technology that can be appreciated and exploited across the recombination field. Recombination plays an important role in the control of genetic stability in human as well as all other living organisms. The discovery that several human cancer prone syndromes, for example, Ataxia Telangiectasia (A-T), Nijmegen Breakage Syndrome (NBS) and A-T like disorder (A-TLD), are caused by defects in double-strand break repair has highlighted the importance of this pathway in maintaining genome integrity and cancer avoidance. Furthermore, the product of the BRCA2 gene, which is mutated in a subset of hereditary breast cancers, interacts directly with Rad51 and is essential for homologous recombination. Many of the invited speakers will discuss the role of proteins defective in these human cancer prone syndromes in genome stability and resistance to environmental mutagens. To inform and augment studies from mammals, work concerning related proteins and mechanisms from model systems of bacteria, yeast, Arabidopsis, Drosophila, C. elegans and Xenopus will be featured. Much of the conference will be devoted to topics of concern to the National Cancer. Public Health Relevance: DNA repair by homologous recombination plays an important role in the control of genetic stability in all living organisms. The discovery that several human cancer prone syndromes, for example, Ataxia Telangiectasia (A-T), hereditary forms of breast cancer (BRCA1 or BRCA2) and Bloom's syndrome are caused by defects in the DNA recombination/repair has highlighted the importance of this pathway in maintaining genome integrity and cancer avoidance. This conference brings together the principal investigators studying the mechanisms of recombination with the goal of further understanding how recombination contributes to genome stability.